1. Field of the Invention
The invention relates to a fluid-conveying machine, particularly, a pump, having a component rotating in a stationary housing part inside an annular gap, the stationary housing part separating an interior having a higher product pressure from an exterior having a lower pressure, and in which the rotating component is mounted in an external bearing which is sealed with respect to the interior via a sealing system.
2. Description of Related Art
A related device is disclosed in DE 43 16 735 C2, which discloses a screw pump having at least one conveyor screw which is surrounded by a housing which has at least one suction connection and at least one pressure connection, the suction connection being connected to a suction chamber connected upstream of the conveyor screw, and the pressure connection being connected to a pressure chamber arranged downstream of the conveyor screw. The housing also has devices for separating the respective liquid phase from the gas phase of the liquid flow emerging from the conveyor screw, and a lower section for holding at least a portion of the separated liquid phase. A liquid short-circuiting line is connected to the lower pressure chamber section. The liquid-short circuiting line is also connected to the suction chamber and, together with the conveying elements, forms a closed circuit for a liquid quantity required for the permanent seal.
Numerous sealing systems have been developed for sealing rotating shafts, but they have proven to be disadvantageous for machines of the aforementioned design. Contactless labyrinth seals are disadvantageous, because of their high rate of leakage resulting from the existence of relatively large gaps, and because no pressure differences can be tolerated at the shaft bushing. Lip seals tolerate only slight pressure differences up to a maximum of 5 bars on the shaft bushing. Soft packings likewise have relatively high rates of leakage, require a high level of outlay and maintenance, and develop a large amount of heat at high rotational speeds. The end face seals used in pumps of advanced design prove to be disadvantageous because of their complex structure and the difficulty of commissioning them.
The difficulties suggested in the preceding are not intended to be exhaustive but rather are among many which tend to reduce the effectiveness and desirability of the known seals. Other noteworthy problems may also exist, however, those presented above should be sufficient to demonstrate that such methods and apparatuses appearing in the past will admit to worthwhile improvement.